The present invention refers to check valves for medical infusion lines and the like. More in particular, the invention regards an anti-siphon (or non-return) valve for such medical lines.
These valves traditionally include a first and a second tubular element mutually coaxial to each other and respectively defining an upstream passageway and a downstream passageway, a diaphragm of elastically deformable material transversely positioned between said first and a second tubular elements and acting as a fluid seal in combination with an annular valve seat to keep the said control valve normally closed, wherein a predetermined fluid pressure in the said upstream passageway causes flexion of the said diaphragm and the consequent opening of the valve.
These valves, which are normally closed, must be capable of promptly opening when the pressure in the upstream passageway exceeds a predetermined threshold. In the particular case of an anti-siphon valve, this threshold is much higher than in the normal check valves used in similar medical applications, and is typically in the range from 1 to 5 psi.
In addition, in some applications and particularly in the case of anti-siphon valves, it must be possible to control the opening of the valve diaphragm independently of the pressure in the upstream passageway. This manoeuvre can be required, for example, in cases of priming a pump (normally a peristaltic pump) associated with the medical line, when the infusion must be given under the effect of gravity, or also when the medical line is washed or bled.
The object of the present invention is to provide a check valve of the above-defined type, designed to meet the aforesaid requirement and with simple and low-cost manufacture, also with regards to assembling.
Another object of the invention is to provide a check valve of the above-defined type, the opening of which can be controlled in an easy and practical manner.
According to the invention, these objects are essentially achieved via the characteristics defined in claim 1.
Additional, advantageous, secondary characteristics of the valve are defined in sub- claims 2-42.